and whenI "Turn On" the responsive behavior (it is possible to turn it off), the images don't have the good size ... I explain : for a 200x200 px image called image.jpg, the
plugin creates a image@2x.jpg file that is a 400x400 px image.

On my New iPad (retina), I can see the image@2x.jpg file BUT the size of the image is 800x800 px (and so, there's a blur effect) ...

If I try the client-side method (retina.js), no more problem : I can see the image@2x.jpg and the iPad displays an image of 400x400 px (same size as a 200x200 px image on a non-retina device). With the client-side method, everything is perfect but ... slow.

If I try now to turn "off" the responsive behavior, the server-side method works fine : I can see the image@2x.jpg and the iPad displays an image of 400x400 px too.

Haha, I am sorry, I didn't quite understand what the problem is :p You can also write directly to me (via Totoro Times) in French (that will be easier for me as well actually, haha :p) and I am especially interested in talking to you if you are using a French version of WordPress too.

But to give you a quick answer already : the client-side used to be very slow BUT the original author of the JavaScript file updated it 3 days ago, I noticed it today, and tried it. It is now fast! It will never be as good as the server-side method, but at least it doesn't block your browser and it is very smooth. I will update the plugin in one hour or two hours, and release a new version. Your website will then work great with the client-side method.

Then later, let's talk by email and try to find a way to make your website to work with the server-side method as well. Deal? :) À bientôt !

Thanks for your answer ... I'll try to be clearer. With the server-side method on my new iPad, it is as if I had activated the debug mode and I was watching the result on my old MacBook : all the image have twice their normal size.

Okay, it's what I was afraid of... Actually with Retina you really need to set a width and height to all your images. But WordPress normally does that automatically when you include them to your posts, isn't it?

By the way, I just release the new version. Try it out, and tell me if it is faster :)

You can see what happens on the unique article "Bonjour tout le monde !"
I tried to determine whether there was a problem with the css applied to images by editing the file responsive.css (I can send it to you if you want it).

I have not really found "width: auto" applied to the images but I tried to remove some css that seemed doubtful. The problem was not solved in this way. Similarly, with Firebug.

This has perhaps unrelated, but I noticed there is a problem with the server-method if I do not activate the permalinks: the plugin does not display the retina version of the image.

You actually probably right on that point: if the permalinks are disabled, the plugin might not work at all. I will give it a shot today.

I just tried your website with my iPhone 4, and the first picture shows well, but the second appears much bigger :p Can you do something for me? On this "Retina" installation, can you set the "Debug Mode" on for Retina? That would help me for my testing ( from non-retina computer, unfortunately I am not always at home with my brand new MBP :( ).

Actually I just realized that "width='300px' height='111px'" was missing in the HTML attributes of your image, that is why! Normally when you insert an image in your post, those attributes are always added. Aren't they added in your case? Did you write the HTML yourself?

The issue for me is clear now: it is when you EDIT the post and INSERT the images. The HTML code for the images must contain the width and height properties but it doesn't. Why? I have no idea, in all my WP installations I always have them. Maybe your theme is running some trick when you insert images and remove those properties? I have no idea...